Question

o numero 1 e 5 são raizes de quais equação? A)x² -6x +5=0 B)x² -3x -10=0 C)2x² +2x -4=0 D)-2x² +12x=-10

Answer 1

A)X² - 6 X + 5 = 0
1² - 6 .1 + 5 = 0
1 - 6 + 5 = 0
-5 + 5 = 0
5² - 6 . 5 + 5 = 0
25 - 30 + 5 = 0
25 - 25 = 0

B)X² - 3 X - 10 = 0
1² - 3 . 1 - 10 = 0
1  - 3 - 10 = 0
1 - 13 = 0
-12 = 0

5² - 3 . 5 + 5 = 0
25 - 15 + 5 = 0
25 - 10 = 0
15 = 0

C)2 X² + 2 X - 4 = 0
2 .1² + 2 .1 - 4 = 0
2 . 1 + 2 - 4 = 0
2+2 -4 = 0
4 - 4 = 0

2.5² + 2 . 5 - 4 = 0
2 . 25 + 10 - 4 = 0
50 + 10 - 4 = 0
60 - 4 = 0
 56 = 0

D)-2 X² + 12 X + 10 = 0
-2.1² + 12 . 1 + 10 = 0
-2 . 1 + 12 + 10 = 0
-2 + 12 + 10 = 0
-2 + 22 = 0
20 = 0

-2 .5² + 12 . 5 + 10 = 0
-2 . 25 + 60 + 10 = 0
- 50 + 60 + 10 = 0
- 50 + 70 = 0
20 = 0

Resposta 1 e 5 são raízes  apenas da letra  A)